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// while (clock()<=69*CLOCKS_PER_SEC)
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define pb push_back
#define SZ(x) ((int)(x).size())
#define ALL(x) x.begin(),x.end()
#define all(x) x.begin(),x.end()
#define fi first
#define se second
#define _upgrade ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define erase_duplicates(x) sort(all(x)); (x).resize(distance((x).begin(), unique(all(x))));


using namespace std;
using namespace __gnu_pbds;
template<typename T>
using ordered_set = tree<
T,
null_type,
less<T>,
rb_tree_tag,
tree_order_statistics_node_update>;

//X.find_by_order(k); - zwraca iterator na k-ty element (numeracja od zerowego)
//X.order_of_key(k); - zwraca liczbę elementów ostro mniejszych niż k

typedef long long LL;
typedef pair<int,int> PII;
typedef pair<LL,LL> PLL;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
typedef vector<LL> VLL;
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<char> VC;
typedef long double LD;
typedef pair<LD,LD> PLD;
typedef vector<LD> VLD;
typedef vector<PLD> VPLD;

template<class TH> void _dbg(const char *sdbg, TH h){ cerr<<sdbg<<" = "<<h<<endl; }
template<class TH, class... TA> void _dbg(const char *sdbg, TH h, TA... a) {
  while(*sdbg!=',')cerr<<*sdbg++;
  cerr<<" = "<<h<<", "; _dbg(sdbg+1, a...);
}

#ifdef LOCAL
#define dbg(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(...)
#define cerr if(0)cout
#endif

const int maxn = (1e6)+7;
const int maxk = 20;
const int inf = (1e9)+7;
const LL LLinf = ((LL)1e18)+7LL;
const LD eps = 1e-9;
const LL mod = 1e9+7;

// ***************************** CODE ***************************** //

int maxi = 0;
int licz = 0;
VPII wek[maxn];
int ogr[maxn];
int cur[maxn];
int ile[maxn];

int start;

void dfs(int x, int f = -1)
{
  if(x < start)
  {
    int ok = 1;
    for(int i = maxi;i > licz && ok == 1;i--)
    {
      if(cur[i] < ogr[i])
        ok = 0;
      else
        if(cur[i] > ogr[i])
          ok = 2;
    }
    if(ok == 1)
      ile[cur[licz]]++;
    if(ok == 0)
      ile[0]++;
  }
  for(auto s : wek[x])
    if(s.fi != f)
    {
      cur[s.se]++;
      dfs(s.fi, x);
      cur[s.se]--;
    }
}

void rob(int x)
{
  start = x;
  for(int i = 0;i <= maxi;i++)
    cur[i] = 0;
  dfs(x);
}

int main()
{
	_upgrade
  int n, k;
  cin>>n>>k;
  for(int i = 1;i < n;i++)
  {
    int a, b, c;
    cin>>a>>b>>c;
    wek[a].pb({b, c});
    wek[b].pb({a, c});
    maxi = max(maxi, c);
  }
  for(int i = 1;i <= maxi;i++)
    ogr[i] = n;
  for(int i = maxi;i >= 1;i--)
  {
    licz = i;
    for(int j = 0;j <= n;j++)
      ile[j] = 0;
    for(int j = 1;j <= n;j++)
      rob(j);
    for(int j = 1;j <= n;j++)
      ile[j] += ile[j - 1];
    while(ogr[i] > -1 and ile[ogr[i]] >= k)
      ogr[i]--;
    ogr[i]++;
  }
  LL res = 0LL;
  LL nn = n;
  for(int i = 1;i <= maxi;i++)
  {
    res = (res + nn * ogr[i]) % mod;
    nn = (nn * n) % mod;
  }
  cout<<res;

	return 0;
}